Why don't you use ceramic stones?

[george wilson]

I have sharpened everything I have just fine on my 2" wide stones,including the 3" blade from my big jointer plane that I have posted here. I just move the blade about while sharpening,to get all of it sharp. No biggie.

Matthew,I have mentioned in my first post here,that an Arkansas stone is terribly soft compared to a ceramic. I easily re grind broken Arkansas slip stones into special shapes. But,only a diamond will cut the ceramics.

Read my initial post again,if you haven't.

You cannot find a steel that the ceramic stones cannot cut. But,I could not get a D2 knife razor sharp on my Arkansas,or any other stone I had at the time. The ceramics sharpened it right up.

[David Weaver]

I have choosers 800, 3000 and a gokomyo 10000 grit water stone. I also bought a soft + hard + black Arkansas stones. Lately I have been realizing that using a oil stone or a stone that needs no oil or flattening is so much nicer for all the reasons George mentioned . It seems more apt to a wood shop than water and I don't have to dry my hands often. Most importantly, I like the resulting edge better. I am going to get a eze lap plate instead of the soft ark as the ark has a hard time removing much from the likes of hock and a2, and I can see where I might one day sell my waterstones. My question to George and David , what is the differance between the ceramic and ark? The hard ark+black combo seems to refine and polish the edge just fine after the burr us reached but they do not make a super bright polish, but the edge cut fantastically. How do the ceramic function in comparison?

The ceramic is much harder than an arkansas stone. If you can believe that. The abrasive in it is probably some sort of ceramic alumina, and the entire thing may be abrasive for all I know (meaning that the stone and binder are generally one material and edges of voids do the cutting and determine the fineness of the stone. This is essentially the same thing for novaculite, except the novaculite particles aren't as hard and durable as ceramic alumina.

Obvious other issue is that if you don't use the spydercos dry, you use water instead of oil. The medium is hard to water, though - it's like very fine coral and the water just disappears.

Since the alumina is harder than novaculite, it stays sharp and cuts carbides that novaculite doesn't.

There is probably some easy reading somewhere to find out exactly what the ceramic bits and pieces are made of. We use the term aluminum oxide loosely, but there are scads of different abrasive aluminas that have different levels of durability and slightly different levels of hardness. Ceramics, etc, have a lot of usefulness in manufacturing, especially in heavy industry, and as woodworkers, we're more or less siphoning off stuff that we can use. We don't care so much about the durability of the alumina as a manufacturing environment might where the item is a wear part.

I have no idea what coors uses the ceramics for, but I'd imagine the reason that they had a ceramic division was to supply their beer making. You can find coors ceramic hones out there, but no guarantees on what they actually are since I'm sure spyderco had a spec and worked with them to get what they wanted.

Anyway, the real difference between them and novaculite is that they can cut carbides and novaculite generally can't.

[Brian Loran]

George, what do you see as the benefit to using ceramic rather than diamond stones? Thanks for the info!

Edit to better frame my question.

Here is what I see when comparing them.

Diamonds cut as fast as ceramic (maybe faster)
Ceramic lasts longer?
neither need flattening
Equivalent mess? not sure about this one

I am probably missing some other important attributes such as one may be finer than the other?

So, what are the main factors/factor for you that made you pick ceramic over diamond stones? longer lasting, better edge, etc...

Thanks.

[David Weaver]

Matt - here's a little bit about carbides, you've probably read it already at some point:

Go down to the knoop hardness table at the bottom of this page:

http://www.tedpella.com/Material-Sci...ng_Systems.htm

Figure tool steel in general (especially plain high carbon) is probably mid to high 700s. Novaculite is probably similar to quartz or just a bit harder (courtesy of google books, knoop from hock's book for novaculite is 820 vs. 780 for 62 hardness steel).

(WAY) up from that are chromium, moly and tungsten carbides. And way up from there are vanadium carbides.

IIRC , D2 that george is talking about has a lot of chromium carbides, and the ceramic alumina or whatever is in the spydercos will cut through them. Novaculite won't. I think some of the turners tools are loaded with vanadium carbides, which is probably why the CBN wheels are so popular.

(I just looked up spyderco to try to find out what flavor of alumina they use, and they don't specify - just alumina, and the matrix is ceramic. I don't know that much about aluminas, but I thought ceramic was a type of alumina or alumina a type of ceramic, anyway - at any rate, they would be one of the few stones where the binder and the abrasives are both hard enough to cut hardened steel)

I never saw novaculite knoop quantified before, but have for a while used novaculite stones to determine how hard japanese white steel tools are. When they are super hard, the novaculite just burnishes them. If they are 62 hardness, as a lot of the budget stuff is, they sharpen just fine on novaculite. It's interesting to see that quantified to justify why that's a good test.

[Jim Koepke]

Why don't you use ceramic stones?

Because I bought everything else before hearing about them.

Just bought another chisel that came with a bit of pitting. A few minutes were spent on a 4' strip of 80 grit sand paper on the granite horse. Then a little time on the Mk II power set up. Then 1000, 4000 and 8000 grit water stones and a few swipes on the green strop and all it needed was a new handle.

During the cold months water freezes in my shop so it is oil stones during that time of year.

There is always something different going on. Just yesterday I was sharpening a shovel.

It will be awhile before any of my stones need replacing. To buy some new ceramics would require a sudden increase in income or a winning lottery ticket.

jtk

[ian maybury]

Ceramics caught my eye as a potentially attractive option for sharpening gouges and the like because of the low wear rate. I couldn't find any conical or round slips though (just flats), and thought as well that there was a shortage of the information needed to allow a comparison with waterstones.

Maybe I just didn't look in the right places???

[Pat Barry]

The ceramic is much harder than an arkansas stone. If you can believe that. The abrasive in it is probably some sort of ceramic alumina, and the entire thing may be abrasive for all I know (meaning that the stone and binder are generally one material and edges of voids do the cutting and determine the fineness of the stone. This is essentially the same thing for novaculite, except the novaculite particles aren't as hard and durable as ceramic alumina.

Obvious other issue is that if you don't use the spydercos dry, you use water instead of oil. The medium is hard to water, though - it's like very fine coral and the water just disappears.

Since the alumina is harder than novaculite, it stays sharp and cuts carbides that novaculite doesn't.

There is probably some easy reading somewhere to find out exactly what the ceramic bits and pieces are made of. We use the term aluminum oxide loosely, but there are scads of different abrasive aluminas that have different levels of durability and slightly different levels of hardness. Ceramics, etc, have a lot of usefulness in manufacturing, especially in heavy industry, and as woodworkers, we're more or less siphoning off stuff that we can use. We don't care so much about the durability of the alumina as a manufacturing environment might where the item is a wear part.

I have no idea what coors uses the ceramics for, but I'd imagine the reason that they had a ceramic division was to supply their beer making. You can find coors ceramic hones out there, but no guarantees on what they actually are since I'm sure spyderco had a spec and worked with them to get what they wanted.

Anyway, the real difference between them and novaculite is that they can cut carbides and novaculite generally can't.

We use CoorsTek ceramics in our products. Primarily, the higher purity grades of Alumina (aluminum oxide). Here is the CoorsTek technical data for their product line which I got from a simple google search.
http://www.coorstek.com/resource-lib...properties.pdf
Common allumina materials range in hardness from (rockwell scale mid 70's thru mid 80's). Particle sizes are several microns. One important aspect is that moisture absorption is 0 for most of these materials.

[Phillip J Allen]

Hi all,

Coors got into the ceramics business during prohibition so they could stay in the black.

I drove over to the Golden Colorado spyderco store and !
bought their round/square/triangle/oval-slip ceramic pencil stones to hone the cutters for my Stanley 45 & 55. They worked well with a bit of 3in1 oil.

I would vote that they are a good bargin and worth buying

[george wilson]

Several questions.

You CAN buy a set of ceramic slip stones which include a round one. You can also buy thicker chef's ceramic sticks that are about 10" long and about 5/8" or 3/4" in diameter. I haven't seen one in person,just pictures. I do have the slipstone set.

When you are sharpening a small V tool,it is fairly easy to soon wear grooves in an Arkansas slip. That won't happen with a ceramic triangular slip stone.

D2 steel has a 12% chromium content. It was designed to be a very high wear resistant tool steel that is used in things like shear blades for shearing steel sheet. I have later on found out that I just can't get(at least) my D2 Queen pocket knife to hold a razor edge. It gets a LITTLE dull,and seems to stay at that stage for a very long time. I don't plan to make any more D2 knives. Besides,it's a difficult steel to work and polish.

Why ceramics over diamond? Diamonds are like permanent sand paper. Good for quickly re establishing an edge,but that edge is not really sharp. I get rid of minor nicks with mine,and that little shiny line that you see on the cutting edge of a dull tool. But,diamond stones leave scratches on the edge. The ceramic stones are many times finer,and leave a finely polished edge.

Now,you could get some super fine diamond abrasives in a tube,or in powder form,and hone your tools on a cast iron plate with them. I know David had done that. I have some,too,for my 200 RPM horizontal/vertical diamond grinder. But,I would only use them on solid carbide tooling for my machine tools. I do not like the idea of letting loose diamond dust get into the shop. If it gets on a machine,it will forever lap the sliding surfaces till the machine is worn out. I even keep the diamond grinder itself well away from my lathes and mills. This is not a grinder most will have as they cost about $3,000.00 for my Sunnen model. Luckily I got mine used,CHEAP. I did have a bench model I bought new for the shop at the museum. Just the 6" ceramic wheel they sell to use diamond paste on is about $275.00 last time I checked. I could do with metal plates,though.

[David Weaver]

I've got diamonds down to a tenth of a micron. They are loose, though. I don't actually use them for anything, I just figured at the time I bought them, I was already buying from the retailer who had them (it might've been us products, or something like that) that I'd get a few vials of 25 carats each of various sized diamonds.

1 or 1/2 micron diamonds after a medium grit diamond hone is actually a very sensible sharpening regime. It's fine enough to avoid that toothy deep-groove feeling that diamonds have. There is nothing remotely close to being resistant to it in any steel, either.

I don't like diamonds for razors, though, which is really what I wanted to try them for, so they sit in their vials and are probably clumped together now.

I wonder if we'll get woodworking retailers selling nanodiamonds at some point (a tougher and harder diamond that what we normally see). Probably not, as the makers seem bent on cheapening the cost to make the hones in the first place, and then making boasts that don't seem to hold water (like how great monocrystalline diamonds are).

[Harold Burrell]

OK...shhhh...while my wife is not looking...

If someone (you know, "a friend") wanted to check out some ceramics...what would be a good manufacturer as well as a good place to get them???

[David Barnett]

1 or 1/2 micron diamonds after a medium grit diamond hone is actually a very sensible sharpening regime. It's fine enough to avoid that toothy deep-groove feeling that diamonds have. There is nothing remotely close to being resistant to it in any steel, either.

Monocrystalline diamond at a given micron grit size will cut deeper than other abrasives. Polycrystalline will cut as fast and faster while leaving shallower, more rounded troughs and a smoother finish. Either diamond crystal habit will cut deeper than other abrasives so one needs a smaller comparable mesh size as one moves down the micron scale.

One strategy is to hollow grind bevels, refining and smoothing on a diamond stone/plate, such as 600 grit, then lapping with a big jump to 1µ (14,000 grit) and 0.5µ if desired. Depending on the tool and the steel, adding a step at 3µ (8,000 grit) then to 1µ works fine but I don't bother. If one prefers not to lap, then 600 grit diamond to ceramic stones, translucent novaculte or waterstones will also do the trick. I also strop as a final step even after sub-micron diamond.

I like the Spyderco ceramics but tend to use them more for gravers and tiny carvers than wider woodworking chisels. For extremely bright cuts in precious metals I like to finish up on jasper, though.

[Christopher Charles]

I recently picked up a set of shapton pro ceramics and atoma diamond plate from Stu (1K, 5K, 12K) and they seem to have all the advantages mentioned by George, though I don't know how they compare to the Spydercos. A quantum leap above the norton set i had before in terms of ease of use if nothing else.

Cheers,
C

[David Weaver]

OK...shhhh...while my wife is not looking...

If someone (you know, "a friend") wanted to check out some ceramics...what would be a good manufacturer as well as a good place to get them???

Spyderco medium and UF or F (but not both). If you're willing to get them in 2x8, they're about $80 for the pair.

[David Weaver]

Monocrystalline diamond at a given micron grit size will cut deeper than other abrasives. Polycrystalline will cut as fast and faster while leaving shallower, more rounded troughs and a smoother finish. Either diamond crystal habit will cut deeper than other abrasives so one needs a smaller comparable mesh size as one moves down the micron scale.

One strategy is to hollow grind bevels, refining and smoothing on a diamond stone/plate, such as 600 grit, then lapping with a big jump to 1µ (14,000 grit) and 0.5µ if desired. Depending on the tool and the steel, adding a step at 3µ (8,000 grit) then to 1µ works fine but I don't bother. If one prefers not to lap, then 600 grit diamond to ceramic stones, translucent novaculte or waterstones will also do the trick. I also strop as a final step even after sub-micron diamond.

I like the Spyderco ceramics but tend to use them more for gravers and tiny carvers than wider woodworking chisels. For extremely bright cuts in precious metals I like to finish up on jasper, though.

The difference in feel (mono vs. polycrystalline) to me is like filing vs. rasping. It's very much like the difference between using a saw that is filed appropriately aggressive vs. a crosscut saw that has such a great deal of fleam that it just rasps the wood. I don't know if most people will gather what that means, so maybe it's better to say that monocrystalline diamonds feel like riding a road bike over cobblestone and polycrystalline diamonds feel like opening a high quality zipper.

It's my opinion that most of the people who don't like diamond hones because they've been using monocrystalline diamonds.

Jasper is super fantastic - a poor man's translucent oilstone, but one with sharper particles.